<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8" />
  <meta http-equiv="X-UA-Compatible" content="IE=edge" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <link rel="stylesheet" href="./css/index.css" />
  <title>记事本</title>
</head>

<body>

  <!-- 主体区域 -->
  <section id="app">
    <!-- 输入框 -->
    <header class="header">
      <h1>小黑记事本</h1>
      <input @keyup.enter="add" v-model.trim="content" placeholder="请输入任务" class="new-todo" />
      <button @click="add" class="add">添加任务</button>
    </header>
    <!-- 列表区域 -->
    <section class="main">
      <ul class="todo-list">
        <li class="todo" v-for="(item, index) in todoList" :key="item.id">
          <div class="view">
            <span class="index">{{ index + 1 }}.</span> <label>{{item.name}}</label>
            <button @click="del(item.id)" class="destroy"></button>
          </div>
        </li>
      </ul>
    </section>
    <!-- 统计和清空 -->
    <footer class="footer" v-show="todoList.length">
      <!-- 统计 -->
      <span class="todo-count">合 计:<strong> {{ todoList.length }} </strong></span>
      <!-- 清空 -->
      <button @click="clear" class="clear-completed">
        清空任务
      </button>
    </footer>
  </section>

  <!-- 底部 -->
  <script src="./../vue.js"></script>
  <script>

    const app = new Vue({
      el: '#app',
      data: {
        todoList: [
          { id: 1, name: '吃火锅' },
          { id: 2, name: '敲代码' },
          { id: 3, name: '学vue' },
        ],
        content: '' // 任务名称
      },
      methods: {
        del(id) {
          this.todoList = this.todoList.filter(item => item.id !== id)
        },
        add() {
          /*
            1. 给按钮注册点击事件
            2. 通过v-model 给表单元素进行双向绑定
            3. 获取到输入框的值
            4. 添加到数组中 末尾 push / 开头 unshift
          */
          if (!this.content) return alert('任务名称不能为空')
          console.log(this.content);
          this.todoList.unshift({
            id: +new Date(), // 时间戳
            name: this.content
          })
          this.content = ''
        },
        clear() {
          this.todoList = []
        }
      }
    })

  </script>
</body>

</html>